why won't my radiator get hot.?

Question

just one radiator in the whole house does not get hot. I have tried bleeding it and it starts getting hot then when I stop it goes cold ageain. Should I bleed radiators with the heating on or off ? What am I doing wrong ?

Answer 1

radiators need bleeding regularly..as air gets trapped at the top and stops the flow..new radiators sometimes get blocked with residue from the sealant..old radiators get blocked by rust..which i think maybe the case with yours ..also there is a regulator at the bottom which adjusts the temperature..so first bleed the radiator..second isolate the radiator concerned and drain the water from the bottom ..this will clear any obstruction..make sure the control for temperature is open full..once this is done close the runoff tap..open the bleed valve..and re-fill by un-isolating the radiator..once the water comes out of the bleed valve close the valve and it should work perfectly..

Answer 2

There is a good chance you only need to bleed this one radiator, because this is where the air is collecting in the system, for one reason or another.

As you bleed the radiator, you will need to top up the pressure in the system, to at least 1.5 bar on your boiler, because you are effectively releasing pressure from the system when you bleed the air out.

To do this you will have to very gradually and carefully fill using the 'loop' or 'flexi hose' found under the boiler, this is fairly easy to do, just remember where the original tap positionings are when you start. Take digital photos of it all, to refer back to it.
This filling up of the system means opening a tap or two taps simultaniously, for just a second or two. You will hear some water and air entering the system as you do this, no doubt with small air bubbles within the mains water like you normally see in a glass of water.

The water that you top up the system with contains more air bubbles that the stuff that has been in your radiators for years, and as it goes into the system it will collect in that very same radiator again!
So you will need to bleed it a little each day. It is a game of fill/let out air/fill let out air ......

This one radiator you mention is affected because it is 'where it is' in the system, it might be the one at the end of the pipe run or the highest up in the house for example.
Or it might be a small rad off a main run that catches the bubbles that pass by on the larger pipe run.

Now if the system keeps it's pressure for a few days, this proves it is not leaking under the floor somewhere, then you will eventually get most of the air out of the system with regular bleeding. Pump it up to 2 bar on the system and it will run more efficiently.

All the air causing the problem won't be released in the first or second attempt until all the tiny air bubbles hav been bled from the system so be patient. This can take a few weeks to do.
There will always be some air in there anyway, but just bleed the system until that rad keeps hot.

Do this when the system is warm/hot and running as normal.

Answer 3

Take the thremostat off (a good firm trun should do the trick) and this should reveal a small pin. Firstly, with your fingers, try to free this up by giving it a slight tug. Be careful not to pull it out so don't pull too hard. If you can't free it up with fingers, try a pair of pliers.

The problem is the pin regulates the flow of water into the radiator by being pushed into and allowed to slide out by the thermostat. Over the summer, the thermostat will have pushed the pin in for an extended period and it has stuck with time.

No need to bleed the radiator unless the top is the only part that is cold.

Hope this helps.

Answer 4

The system needs balancing meaning that the offending radiator needs more hot water.Do this by turning down the hot water supply valve on each radiator a little this is on the left hand side.It is all a matter of trial and error and with patience it will work.The system will need to be running during the adjustement.

Answer 5

Bleed the radiator with the heater on. If it is a hot water heater bleed it into a towel until water comes out. Also you may try bleeding all the radiatorsstarting with the one closest to the heater. If its steam heated do the same process, be careful to use a towel to mprotect your hands.

Answer 6

You may need to add water to your system. Then after about a half an hour bleed all the radiators again to see if this works. If not, call a repair man, it's the safer way to deal with a heater problem..

Good Luck...

Answer 7

I have to ask this question,,,,,,,,,Did the radiator ever heat up ?, I went to a house with a similar problem, and after many hours work found that the flow and return were connected tp the same source.
If not go with "stitched up"

Answer 8

Bleed ALL the radiators.

Answer 9

Sounds like the rad needs flushing. Knocks and banging are also tell tale signs of blockages / sludge issues.
I'd be tempted to isolate it, by valving off and disconnecting rad from the rest of the system. Lift if off brackets, take rad outside, upend and flush through thoroughly using a garden hose. Just choose a reasonable fine day - before getting the spanner out!

Answer 10

If it is thermostatic, (has numbers on), remove the head, either a knurled ring or a clamp with a screw tightener, tap the pin underneath untill free, refit the head, all done, if this does not change anything, you need a powerflush, British gas £650 anybody else at least £200 less, company I work for does this for £300.